title: Experimental bovine spongiform encephalopathy: detection of PrP(Sc) in the small intestine relative to exposure dose and age.
abstract: European regulations for the control of bovine spongiform encephalopathy (BSE) decree destruction of the intestines from slaughtered cattle, therefore producers have been obliged to import beef casings from countries with a negligible BSE risk. This study applies immunohistochemical and biochemical approaches to investigate the occurrence and distribution of disease-associated prion protein (PrP(Sc)) in the duodenum, jejunum and ileum of cattle orally exposed to a 1 g or 100 g dose of a titrated BSE brainstem homogenate. Samples were derived from animals at various times post exposure. Lymphoid follicles were counted and the frequency of affected follicles recorded. No PrP(Sc) was detected in the duodenum or jejunum of animals exposed to a 1 g dose or in the duodenum of animals receiving a 100 g dose. PrP(Sc) was detected in the lymphoid tissue of the ileum of 1/98 (1.0%) animals receiving the 1 g dose and in the jejunum and ileum of 8/58 (13.8%) and 45/99 (45.5%), respectively, of animals receiving the 100 g dose. The frequency of PrP(Sc)- positive follicles was less than 1.5% per case and biochemical tests appeared less sensitive than immunohistochemistry. The probability of detecting lymphoid follicles in the ileum declined with age and for the 100 g exposure the proportion of positive follicles increased, while the proportion of positive animals decreased with age. Detection of PrP(Sc) in intestinal neural tissue was rare. The results suggest that the jejunum and duodenum of BSE-infected cattle contain considerably less BSE infectivity than the ileum, irrespective of exposure dose. In animals receiving the low exposure dose, as in most natural cases of BSE, the rarity of PrP(Sc) detection compared with high-dose exposure, suggests a very low BSE risk from food products containing the jejunum and duodenum of cattle slaughtered for human consumption.
authors.affiliation: Molecular Pathogenesis and Genetics Department, Veterinary Laboratories Agency, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK. m.j.stack@vla.defra.gsi.gov.uk
authors.forename: M J
authors.initials: MJ
authors.lastname: Stack
authors.forename: S J
authors.initials: SJ
authors.lastname: Moore
authors.forename: A
authors.initials: A
authors.lastname: Vidal-Diez
authors.forename: M E
authors.initials: ME
authors.lastname: Arnold
authors.forename: E M
authors.initials: EM
authors.lastname: Jones
authors.forename: Y I
authors.initials: YI
authors.lastname: Spencer
authors.forename: P
authors.initials: P
authors.lastname: Webb
authors.forename: J
authors.initials: J
authors.lastname: Spiropoulos
authors.forename: L
authors.initials: L
authors.lastname: Powell
authors.forename: P
authors.initials: P
authors.lastname: Bellerby
authors.forename: L
authors.initials: L
authors.lastname: Thurston
authors.forename: J
authors.initials: J
authors.lastname: Cooper
authors.forename: M J
authors.initials: MJ
authors.lastname: Chaplin
authors.forename: L A
authors.initials: LA
authors.lastname: Davis
authors.forename: S
authors.initials: S
authors.lastname: Everitt
authors.forename: R
authors.initials: R
authors.lastname: Focosi-Snyman
authors.forename: S A C
authors.initials: SA
authors.lastname: Hawkins
authors.forename: M M
authors.initials: MM
authors.lastname: Simmons
authors.forename: G A H
authors.initials: GA
authors.lastname: Wells
mesh_terms: D000375:Aging; D000818:Animals; D002417:Cattle; D016643:Encephalopathy, Bovine Spongiform / Q000378:metabolism*; D007150:Immunohistochemistry; D007421:Intestine, Small / Q000378:metabolism*; D010581:Peyer's Patches / Q000378:metabolism; D018620:PrPSc Proteins / Q000378:metabolism*
chemical_list: D018620:PrPSc Proteins